We conduct simulation study on the typical influencing factors for negative pressure wave in liquid pipeline leakage. We first analyse the liquid pipeline leakage detection based on negative pressure wave method and o...We conduct simulation study on the typical influencing factors for negative pressure wave in liquid pipeline leakage. We first analyse the liquid pipeline leakage detection based on negative pressure wave method and obtain the essential simulation parameters. Then based on the physical model of pipeline and by introducing leakage boundary condition, we simulate the variation of pressure and flow rate in pipeline after leakage, the influence of leakage scale and leakage position on the pressure and flow rate in the pipeline. The results show that the leakage scale mainly influences the amplitude of negative pressure wave, and that the leakage position inflnenees both the amplitude and the shape of the curves of negative pressure wave.展开更多
A mathematic model is built up to analyze the influences of a pilot valve'sleakage on the performances of pneumatic pressure proportional valve, and the performances aresimulated by using MATLAB. The results indic...A mathematic model is built up to analyze the influences of a pilot valve'sleakage on the performances of pneumatic pressure proportional valve, and the performances aresimulated by using MATLAB. The results indicate that using slide pilot valve in the valve system isfeasible, but the leakage's influences can not be neglected, especially it may induce instability ina low output pressure situation. A pilot valve using too large throttle window will cause the valveoscillate. To improve the working condition of pilot valve, a method adopting different widths oftwo throttle window is proposed. According to our simulation, this method balances the pressure dropbetween the two stage throttle ports, and reduces the influences of pilot valve's leakage.展开更多
A fuzzy robust nonlinear controller for hydraulic rotary actuators in flight motion simulators is proposed. Compared with other three-order models of hydraulic rotary actuators, the proposed controller based on first-...A fuzzy robust nonlinear controller for hydraulic rotary actuators in flight motion simulators is proposed. Compared with other three-order models of hydraulic rotary actuators, the proposed controller based on first-order nonlinear model is more easily applied in practice, whose control law is relatively simple. It not only does not need high-order derivative of desired command,but also does not require the feedback signals of velocity, acceleration and jerk of hydraulic rotary actuators. Another advantage is that it does not rely on any information of friction, inertia force and external disturbing force/torque, which are always difficult to resolve in flight motion simulators. Due to the special composite vane seals of rectangular cross-section and goalpost shape used in hydraulic rotary actuators, the leakage model is more complicated than that of traditional linear hydraulic cylinders. Adaptive multi-input single-output（MISO） fuzzy compensators are introduced to estimate nonlinear uncertain functions about leakage and bulk modulus. Meanwhile, the decomposition of the uncertainties is used to reduce the total number of fuzzy rules. Different from other adaptive fuzzy compensators, a discontinuous projection mapping is employed to guarantee the estimation process to be bounded. Furthermore, with a sufficient number of fuzzy rules, the controller theoretically can guarantee asymptotic tracking performance in the presence of the above uncertainties, which is very important for high-accuracy tracking control of flight motion simulators.Comparative experimental results demonstrate the effectiveness of the proposed algorithm, which can guarantee transient performance and better final accurate tracking in the presence of uncertain nonlinearities and parametric uncertainties.展开更多
文摘We conduct simulation study on the typical influencing factors for negative pressure wave in liquid pipeline leakage. We first analyse the liquid pipeline leakage detection based on negative pressure wave method and obtain the essential simulation parameters. Then based on the physical model of pipeline and by introducing leakage boundary condition, we simulate the variation of pressure and flow rate in pipeline after leakage, the influence of leakage scale and leakage position on the pressure and flow rate in the pipeline. The results show that the leakage scale mainly influences the amplitude of negative pressure wave, and that the leakage position inflnenees both the amplitude and the shape of the curves of negative pressure wave.
基金This project is supported by National Natural Science Foundation of China (No.50122115)the National 10th Five Years Plan Special Research Programs of China(No.2003BA408B14).
文摘A mathematic model is built up to analyze the influences of a pilot valve'sleakage on the performances of pneumatic pressure proportional valve, and the performances aresimulated by using MATLAB. The results indicate that using slide pilot valve in the valve system isfeasible, but the leakage's influences can not be neglected, especially it may induce instability ina low output pressure situation. A pilot valve using too large throttle window will cause the valveoscillate. To improve the working condition of pilot valve, a method adopting different widths oftwo throttle window is proposed. According to our simulation, this method balances the pressure dropbetween the two stage throttle ports, and reduces the influences of pilot valve's leakage.
基金supported by the National Basic Research Program of China(No.2014CB046406)the National Natural Science Foundation of China(No.51235002)
文摘A fuzzy robust nonlinear controller for hydraulic rotary actuators in flight motion simulators is proposed. Compared with other three-order models of hydraulic rotary actuators, the proposed controller based on first-order nonlinear model is more easily applied in practice, whose control law is relatively simple. It not only does not need high-order derivative of desired command,but also does not require the feedback signals of velocity, acceleration and jerk of hydraulic rotary actuators. Another advantage is that it does not rely on any information of friction, inertia force and external disturbing force/torque, which are always difficult to resolve in flight motion simulators. Due to the special composite vane seals of rectangular cross-section and goalpost shape used in hydraulic rotary actuators, the leakage model is more complicated than that of traditional linear hydraulic cylinders. Adaptive multi-input single-output（MISO） fuzzy compensators are introduced to estimate nonlinear uncertain functions about leakage and bulk modulus. Meanwhile, the decomposition of the uncertainties is used to reduce the total number of fuzzy rules. Different from other adaptive fuzzy compensators, a discontinuous projection mapping is employed to guarantee the estimation process to be bounded. Furthermore, with a sufficient number of fuzzy rules, the controller theoretically can guarantee asymptotic tracking performance in the presence of the above uncertainties, which is very important for high-accuracy tracking control of flight motion simulators.Comparative experimental results demonstrate the effectiveness of the proposed algorithm, which can guarantee transient performance and better final accurate tracking in the presence of uncertain nonlinearities and parametric uncertainties.
